I do agree with you that FBX is a extremally hard file format.
It seem liek a Frankenstein of format, what is more frustration is that you get diffrent results base of who you read a file, for example you get a complete different hierarchy if you read the nodes transform or if you apply an animation.
I followed the instruction in thsi docs,
http://docs.autodesk.com/FBX/2013/ENU/FBX-SDK-Documentation/index.html
and I managed to get a converter, but as soon as I try to get animations, the model you get when applying this recommendation to evaluate an animation is very diffrent that the one you get from their recommendation to load a mesh.
I know is I who is wrong, because when I load any BDX file in max the look correct, however file exported by the same Max plugin in look diffrent in other app like Blende or Assimp
teh problem I have with GLFT is that I when to the website to get information
https://www.khronos.org/gltf/
and the was not standard SDK, of Documentation all I saw was specifications, and new specifications.
ther was not Max plugin that can import and expert to 3dsMax.
what I do no like is that to figure out hwo something work, I have to download someone application and reverse engineer what the has done. that not what I do.
writing a Parcel for yet another grammar is not on my radar unless I can figure out the FBX secret which turn out to be harder than I anticipated.